English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In hepatocytes precultured for 24 h with dexamethasone glucagon increased phosphoenolpyruvate carboxykinase activity 3-4-fold with a half maximal activity increase at 30 pM. The half maximal effective glucagon concentration was enhanced 10-fold to 300 pM when insulin was added simultaneously. The glucagon-insulin antagonism was maximally expressed when glucagon was present at low physiological concentrations. At equimolar doses it was only in the concentration range around 0.1 nM that glucagon and insulin became powerful antagonists; at higher levels glucagon was the dominant hormone. In hepatocytes not pretreated with dexamethasone glucagon still enhanced phosphoenolpyruvate carboxykinase activity, but the half maximal effective dose raised more than 30-fold to 1 nM. The degree of stimulation, however, remained essentially unchanged. Thus dexamethasone shifted the glucagon sensitivity of the cells into the physiological concentration range; it exerted a half maximal effect at 10 nM. Dexamethasone was not required for the enzyme induction proper if the cells had been pretreated with the glucocorticoid. The amount of the glucagon-stimulated enzyme induction was dependent on the time period of cell pretreatment with dexamethasone. Glucagon enhanced enzyme activity to the same constant suboptimal level irrespective of whether cells had been pretreated with glucocorticoid for 1 or for 14 h. If cells were pretreated for more than 15 h, glucagon linearly increased enzyme activity further until the maximal value was reached after 24 h pretreatment. The glucagon-insulin antagonism and the glucagon-glucocorticoid synergism were observed at physiological hormone concentrations indicating that the interaction should be effective also in vivo. Dexamethasone does not seem to be generally permissive for the inducing action of glucagon, but rather sensitizes the cell towards lower physiological hormone concentrations.

The Glucagon-Insulin Antagonism and Glucagon-Dexamethasone Synergism in the Induction of Phosphoenolpyruvate Carboxykinase in Cultured Rat Hepatocytes